Children/Infants are required to have their own passport or ID card (for flights within the EU or Schengen area).
It is the responsibility of the parents/guardians to ensure children are holding the proper documentation and appropriate valid travel documents for their travel.
If the child/infant is accompanied only by one of the parents, it is recommended that you have a letter of consent (certified by a public authority) by the other parent. If none of the parents is accompanying the child, it is recommended that the letter of consent is signed by both parents. Letter of consent should preferably be in English language.